The following is a post in its entirety from a UV bulb testing group. Frances is part of the uvguide.co.uk website that is so widely referenced for UV lamp information. They tested the new Solar Glo bulbs since the bulb has been changed and the results are very disappointing. A full report will be sent to the manufacturer and posted on their uvguide website soon. The also have some interesting results on specific brands of compact lamps.

"Here are some key meter results from the tests I've recently completed on ExoTerra Solar Glo lamps with externally frosted glass (ie. the outside of the front of the bulb has a soft matt texture like ground-glass, and if you wet it with a damp finger it becomes more see-through (when not in use, of course!)

My memory must be having problems at the moment. I have tested six of these, not four as I said on Thursday, ..because Rolf C Hagen sent me two of each type, and Dawn sent me one of each.

125-watt lamps:
Lamp 1: Purchased Oct-Nov 2009 by Dawn C., unused, and sent to me in March 2010.
Total UVB after burning-in (105hrs):
10 ins: 232 uW/cm2
12 ins: 160 uW/cm2
18 ins: 70 uW/cm2
UV Index:
10 ins: 8.8
12 ins: 6.1
18 ins: 2.5
This lamp was operating at 115 watts.

Lamp 2:Sent by Rolf C Hagen in March 2010, stated to be "new product"
Total UVB after burning-in (105hrs):
10 ins: 40 uW/cm2
12 ins: 29 uW/cm2
18 ins: 13 uW/cm2
UV Index:
10 ins: 0.9
12 ins: 0.6
18 ins: 0.3
This lamp was operating at 136 watts.

Lamp 3:Sent by Rolf C Hagen in March 2010, stated to be "new product"
Total UVB after burning-in (105hrs):
10 ins: 35 uW/cm2
12 ins: 25 uW/cm2
18 ins: 12 uW/cm2
UV Index:
10 ins: 0.9
12 ins: 0.6
18 ins: 0.2
This lamp was operating at 141 watts.

160-watt lamps:
Lamp 1: Purchased Sept 2009 by Dawn C., used for about 100hrs, and sent to me in March 2010
Total UVB after about 100hrs:
10 ins: 90 uW/cm2
12 ins: 64 uW/cm2
18 ins: 29 uW/cm2
UV Index:
10 ins: 3.5
12 ins: 2.5
18 ins: 1.0
This lamp was operating at ONLY 115 watts - although 160W was stamped on the lamp itself, so it is not one that "got in the wrong box".

Lamp 3:Sent by Rolf C Hagen in March 2010, stated to be "new product"
Total UVB after burning-in (105hrs):
10 ins: 75 uW/cm2
12 ins: 55 uW/cm2
18 ins: 26 uW/cm2
UV Index:
10 ins: 2.0
12 ins: 1.4
18 ins: 0.7
This lamp was operating at 173 watts.

Lamp 3:Sent by Rolf C Hagen in March 2010, stated to be "new product"
Total UVB after 1hour (I have not burned-in this lamp):
10 ins: 43 uW/cm2
12 ins: 31 uW/cm2
18 ins: 15 uW/cm2
UV Index:
10 ins: 0.8
12 ins: 0.5
18 ins: 0.2
This lamp was operating at 159 watts.

Spectra:
The 125W lamp purchased by Dawn in October-November 2009 was presumably manufactured before the change in specs - it is very different - the only one with what I would describe as a "good" spectrum. It has no un-natural short-wavelength UVB below 295nm and a good spectrum for a mercury vapour lamp, with a small peak at 297nm and larger peaks at longer wavelengths still.
None of the other lamps had any UVB below 300nm, in fact hardly anything below 313nm. This is why they give such very low readings with the meters, of course.

I am about to write a full report for ExoTerra/Rolf C Hagen. I will be interested to hear their comments. These are very disappointing results. A high-quality UVB fluorescent tube such as an Arcadia D3+ 12% or a ZooMed Reptisun 10.0 tube can have a UV Index reading between 0.7 - 1.0 at 12" after burning-in -which is better than two of these mercury vapour lamps with the new specifications!

But there is still Darren's lamp with the inner coating, unaccounted for... Maybe the company has discovered the problem already and the lamp Darren received is supposed to be a better replacement???
I expect we'll know more soon...

Frances"